Influence of Sedentary and Active Behaviors on Insulin Sensitivity and Glucose Uptake

Abstract: This article summarizes the effects of inactivity and exercise on muscle glucose uptake and insulin sensitivity. An important determinant of insulin sensitivity in humans, the insulin-induced glucose uptake in skeletal muscle, has been found to be markedly enhanced in trained individuals compared with sedentary controls. Available evidence indicates that the enhanced insulin action is not a genuine training effect, but merely a lasting effect of the previous exercise sessions. Insulin sensitivity increases with single and multiple exercise sessions, and this increase is related to age. The effect disappears after few. The exercise-induced reduction in muscle glycogen is an important factor underlying the increased insulin sensitivity in the period after exercise. Adaptations, which might underlie the increased insulin sensitivity in trained individuals, include increases in levels of the glucose transporter protein GLUT-4 and in muscle glycogen synthase activity, a decrease in the serum triglyceride concentration and, possibly, an increase in the muscle capillary network.